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Configuring Secure SSH Access to an EC2 Instance

You configured SSH access manually using ssh-keygen, enabling secure, passwordless login by linking your local key pair with the server’s authorized_keys.

🎯 Objective

Enable passwordless SSH access by:

Generating SSH keys on local machine
Copying public key to server
Connecting securely via SSH

🧠 Concept

Private Key (id_rsa) → stays on client (never share)
Public Key (id_rsa.pub) → added to server
Server verifies key → grants access without password

⚙️ Step-by-Step (Your Actual Flow)

🖥️ On Client Machine

1️⃣ Navigate to SSH Directory

plain text
cd /root/.ssh
ls -lah

2️⃣ Generate SSH Key Pair

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ssh-keygen

👉 Generates:

plain text
id_rsa       (private key)
id_rsa.pub   (public key)

3️⃣ View Public Key

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cat id_rsa.pub

👉 Copy this key

🌐 On Remote Server

4️⃣ Login (Initial - Password Based)

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ssh root@18.207.121.91

5️⃣ Navigate to SSH Directory

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cd ~/.ssh
ls -lah

6️⃣ Add Public Key

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vi authorized_keys

👉 Paste copied id_rsa.pub

7️⃣ Verify Key Added

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cat authorized_keys

🔐 Final Test

8️⃣ SSH Without Password

plain text
ssh root@18.207.121.91

✅ Should login without password

🔒 Important Permissions

plain text
chmod700 ~/.ssh
chmod600 ~/.ssh/authorized_keys

⚠️ Common Issues

❌ Permission Denied

Check file permissions
Ensure correct key pasted

❌ SSH Still Asking Password

Wrong user (root vs ec2-user)
Key not saved correctly
SSH config issue

🧪 Validation Checklist

[ ] SSH key generated
[ ] Public key copied to server
[ ] authorized_keys updated
[ ] Permissions set correctly
[ ] Passwordless SSH works

📌 Summary

You configured SSH access manually using ssh-keygen, enabling secure, passwordless login by linking your local key pair with the server’s authorized_keys.